Worm/Tentacle/Tail/Spine Animation with ease
Consider using a Spline IK on the armature.



In the animation above the influence of the constraint is keyframed.


Animate the curve as part of your animation.
Animate influence of Spline IK constraint as part of your animation.
Your bones will flow fluidly under the control of the curve.
Save poses.  Many options.


Attach this in pose mode.



Bones in yellow conforming to a curve.  Influence is 1.0 full strength.  The image above.

No bone stretching is depicted here to have length constant.  You are the artist. You can change the setting.

The target curve of the constraint beveled in blue. The image above.



Constraint influence set to 0.0.  No strength.  Bone are [parallel] to XY plane [ground].  Image above.



In the image above you see the curve in edit mode and the bevel for visibility.  You need not render the curve.



In the image above we see only the final bone positions.  The last bone was selected for the IK Spline Constraint.  The chain length specifies how many previous bones are included.



Animation data in graph editor for the Spline IK Constraint Influence.